1. Field of the Invention
The present invention relates to a substrate processing apparatus that processes substrates.
2. Description of the Background Art
Substrate processing apparatuses have been used to carry out various kinds of processing to substrates such as semiconductor wafers and glass substrates for a photomask, a liquid crystal display, and an optical disk.
For example, JP 2004-146708 A discloses a substrate processing apparatus that includes a reversing unit that reverses the top surface and the back surface of a substrate. In the disclosed substrate processing apparatus, a center robot (transport unit) that transports a substrate is arranged substantially in the center of the rectangular processing section.
In the processing section, a plurality of (four, for example) back surface cleaning units that carry out cleaning processing to the back surfaces of substrates are provided to surround the center robot. Furthermore, the reversing unit is arranged in a position accessible by the center robot in the processing section.
On one end side of the processing section, an indexer section including a plurality of storing containers that store substrates is provided. The indexer section is provided with a substrate transport robot that takes out a substrate prior to processing from a storing container or stores a substrate after processing in a storing container.
In this configuration, the substrate transport robot takes out a substrate prior to processing from any of the storing containers and delivers the substrate to the center robot and receives a substrate after processing from the center robot to store the substrate to any of the storing containers.
Upon receiving a substrate prior to processing from the substrate transport robot, the center robot delivers the received substrate to the reversing unit. The reversing unit reverses the substrate received from the center robot so that the top surface of the substrate is directed downward. The center robot then receives the substrate reversed by the reversing unit and carries the substrate into any one of the back surface cleaning units.
Subsequently, when the processing in the above-described back surface cleaning unit ends, the center robot takes out the substrate from the back surface cleaning unit and delivers the substrate again to the reversing unit. The reversing unit reverses the substrate so that the top surface of the substrate processed in the back surface cleaning unit is directed upward.
The center robot receives the substrate reversed by the reversing unit and delivers it to the substrate transport robot. The substrate transport robot stores the processed substrate received from the center robot in a storing container.
In this way, a substrate prior to processing stored in a storing container is reversed by the reversing unit to be subjected to processing (to the back surface of the substrate) in the back surface cleaning unit, then again reversed by the reversing unit, and stored in a storing container as a processed substrate.
In the above-described substrate processing apparatus, during the transport of the substrate among the transport robot, the back surface cleaning unit, and the reversing unit, the center robot holding the substrate rotates around the vertical axis.
Therefore, the time for transporting a substrate depends on the rotating angle of the center robot. More specifically, during the transport of a substrate among the transport robot, the back surface cleaning unit, and the reversing unit, as the rotating angle of the center robot increases, the time for transporting the substrate is prolonged.
Here, in the above-described substrate processing apparatus, the reversing unit is provided at the other end side of the processing section. That is to say, the center robot is positioned between the substrate transport robot of the indexer section and the reversing unit.
In this way, the center robot has to rotate during the transport of a substrate between the indexer section and the reversing unit by 180 degrees each before and after the processing. Further, in order to deliver a substrate prior to processing reversed by the reversing unit to a back surface cleaning unit, the center robot also has to rotate a prescribed angle more from the direction directed to the reversing unit. Therefore, throughput improvement in the substrate processing is limited.